PROJECT SUMMARY Personal sound amplification products (PSAPs) have recently become available to the public. PSAPs serve a potentially important role in providing audibility of sounds for adults who have difficulty hearing in some daily living situations, but may not be candidates for traditional, high-amplification hearing aids. Fewer than 20% of adults with hearing loss reporting use of hearing aids, citing high costs of devices and professional care appointments as the most common reasons for not wanting to try amplification. PSAPs are far less expensive than hearing aids, and have recently become an amplification option for people who are not ready, or are unwilling, to wear a hearing aid. Current PSAPs on the market tend to be pre-programmed with standard algorithms, or utilize volume and frequency equalizers that are adjusted by inexperienced users, with wide range in cost and benefit. The proposed product is a smartphone application functioning as a PSAP; this PSAP app would personalize and optimize sounds for individual listeners. With the exceptionally large adoption of smartphone technology across a wide range of demographics, a smartphone PSAP application has the potential to be highly significant to a large segment of US adults. The long-term goal is to develop a high-performance, convenient, low-cost PSAP, in the form of a smartphone app, to bring improved hearing to those who desire amplification in daily life. The objective of the proposed project is to conduct a within-subject, Phase I feasibility clinical trial to optimize a smartphone application that will allow users to perform a self-administered hearing test and customization of sound output for optimal sound quality and benefit. To achieve the objective of this project, we propose the following two specific aims: 1) Optimization of a self-administered hearing test within the smartphone application PSAP, and 2) Assessment of the feasibility of a custom-fit algorithm within the smartphone application PSAP. This Phase I project aims to examine the feasibility of our smartphone application PSAP for: 1) auditory threshold testing, and 2) customized fitting. By comparing unamplified, default prescriptive gain, and user- based fine-tuned gain conditions, this project would significantly advance scientific knowledge and clinical practice in our hearing field. The significance of this project is the development of a convenient, affordable, personal amplification option that overcomes current consumer barriers, is personalized and optimized for their hearing condition, and can positively impact quality of life and potentially reduce the risk of developing medical comorbidities associated with hearing loss.